Gyro

After the ice storms of late. What air pressure should I use for ice covered streets?

FREEBIRD1

We had the same thing here a few days ago, you could not even walk on it, I would advise not to ride on that surface, just me.

Gyro

I didn't try, was wondering if it was possible.

FREEBIRD1

The fatties will handle rough ice at 4-5 PSI to get a good squish, the frozen rain coated stuff has almost no friction, it's almost like oil.. I have seen people ride frozen lakes with studded tires.

DangerousDanR

Toward the end of winter here we get thaw, freeze, thaw, freeze cycles that turn things into a sheet of ice. I switch over to studded tires until the ice is gone.

FREEBIRD1

It got to 40° F nice and sunny, snow turned to the consistency of a milkshake, at least I got to get out.

79pmooney

Bring a pump. Drop the pressure until you fell as secure as you are going to get. Add a few strokes of air if you need to keep your rims off the pavement (pinch flats and rim damage). I didn't own a car in the '70s. Lived in Boston and Ann Arbor. Bike was my sole transportation. The really icy days I rode tubulars near flat and by this time of winter, my rims were approaching irregular polygons for shape. Cyclocross tires and cheap, soft metal rims.

On ice, the best pressure is so soft the tires feel squirmy on the pavement. Yes, pavement cornering is reduced a lot. That might bai you out when you hit the ice.

Gyro

We had a melt over night and I got out on the mush. Wasn't too bad. I guy I know races motorcycles on a lake near here. Check out the studs he's running. The lake didn't freeze over enough to ride this year.https://www.facebook.com/photo/?fbid=6600915892451

Thanks all for the help!

thorstein

Another thing to keep in mind with studs is that if there is a light snow over ice, the studs may not be able to reach the ice through the snow & then you're really no better than non-studded tires. This probably isn't a frequent concern, but worth keeping in mind.

Daniel4

I used to ride on 5psi but I think there's too much rolling resistance. I took a ling ride once and it wore me out. Five hours when it normally would have been three.

Nowadays I ride on 8 psi. Not too much to bounce like a basket ball.

pipeliner

If you ride low pressure, you are much better off going tubeless. Studs are a very good idea but can be annoyingly noisy when riding dry surface. Not all studded tires are equal either. Higher stud count means better traction on ice.

prj71

Doesn't matter if it's 1psi or 10 psi on ice covered streets. It won't make a difference. Tire will still slide all over.

You want studded fat bike tires

Hypno Toad

Studs are the only answer to ice, it's true with its 35 mm tires or 4" tires (Top Contact Winter tires are the only exception to this rule ... and they don't make it for fatbikes). With studded tires, you want high pressures for icy conditions, for me (170 lbs / 77 kg), I ride 12-14 psi with Dillinger 4 tires. The only draw back, at these high pressures, deep snow is very difficult to ride. This YouTube edit from a race on a frozen Lake Minnetonka shows my high pressure tires are great on the bare ice, and I struggle (& fall) in the deep snow.

Gyro

Nice vid Thanks

What speeds were you hitting during the race?

Hypno Toad

I was holding 12 mph on the bare ice, maxing out around 16 mph. The bare ice rolls fast, if you don't get nervous and think too much about going down.

elcruxio

Why do you need high pressures for studs? I've been fine with 6 and 5 psi for... uuh... I think me and the bike are probably around 300lbs.

Daniel4

I've ridden on 5psi for a few years. Too much rolling resistance. Now I'm on 8psi. It's a little bouncy but I can go faster, and longer without getting so tired.

UnCruel 

I've been thinking about this. My limited experience with studs on ice so far has been good with low pressure.

However, in addition to being a measurement of air pressure inside the tire, PSI is also the amount of contact pressure between the tire and the road surface. A tire with low pressure will deform around its studs, and more of the tire between studs will support the weight of the bike and rider. The area around the stud not contacting the road translates to force being applied downward on the stud (into the road/ice). If that area is about a square inch, and the tire is inflated to 5 PSI, then that means the stud only has 5 pounds of force pushing it into the ice. Higher air pressure will cause the tire to deform less, resulting in more of the tire's surface standing away from the road surface and directing pressure through the stud instead, and the pressure being directed toward that stud will be greater. Both factors would combine to produce much more force behind each stud, resulting in more penetration into ice?. In theory, higher pressure should make studs more effective.

On the other hand, lower pressure means the tire deforms more and the contact surface of the tire against the road is larger. The result is that more studs will make contact with the road/ice. The design of the tire is certainly a factor.

It may be that these two things basically cancel each other out, and the direct effect of tire pressure is minimal. The math, geometry, and fluid dynamics are certainly beyond my ability to calculate. There's probably a way to measure the relative effectiveness. Probably, other benefits of high or low tire pressure are more relevant.

CrimsonEclipse

As stated above, studded tires.
Use the PSI that's comfortable.
Don't worry about snow covered ice with studs.
If you hit ice, the studs will take care of it, if you float above the ice with studs, the tire takes care of it.

Hypno Toad

This Toad bikes through Minnesota's winters, and you have the correct theory: higher pressure allows the studs to get better purchase on the ice. Lower tire pressure allows the tire to deform around the studs, just like riding low pressure smooth out a rooted/rocky single track. OTOH no amount of rubber/tire contact is going to help you with ice (Continental Top Contact Winter tires are the only exception I know, and there's not fat tire version available).

To be clear, tire pressures for winter/ice are a complex equation, take the video I posted above, most riders have studded tires and it's the tire pressure the separates the riders falling and the ones riding through (bike-handling skills too). In the video, this Toad is running a high pressure because I knew the lake was mostly bare ice, but that's also why you'll see that I fall in the deep snow between to islands. If you ever watch pro CX, the commentators say during tough races: you want to use the tires/pressure that will be fastest on most of the course and just struggle with the short bits were your tires aren't ideal.